Tuesday, 29 April 2014

April 2014: Melissa Fales on male testosterone

This month, in our fifth anniversary episode (WUHOO!), I speak to Melissa Fales of UCLA about her new research on men’s hormone levels and how they vary over the course of their girlfriend’s menstrual cycle. We’ll also look at two other experiments on ovulation and attraction out this month: one on relationship conflict, and another on the sexual allure of musicians.

4 comments:

Anonymous
said...

Thing is, how important was female choice in prehistoric times? The amount of reproductive choice women have today is only a modern phenomenon made possible by our modern peaceful societies. In the savage prehistoric societies in which we evolved women and girls were treated like property by the men, didn't have much say in who they got married to at a young age and were probably frequently raped if they didn't have male protectors. Prehistoric women don't seem to have been able to exercise much reproductive choice by cheating on their husbands during their fertile window either because the cuckoldry rate in modern HG societies is typically less than 5%.

It is likely, as you say, that women exercised less control over their mate choice in prehistoric times. However, this doesn't mean that they had no choice at all. In fact, one theory suggests that women experience ovulatory preference shifts precisely so that they can exercise choice outside of their primary relationships. Other non-human primates (and birds, too) "cheat" on their primary partners as a way of exercising choice over sexual partners.

And 5% (the estimates vary, so I don't know how solid this figure is) isn't too low to me. If it's correct, it's still one in 20 offspring. Men should still care about trying to reduce that number. If you were told a certain behaviour had an associated cancer risk of 1 in 20, you would probably stop performing that behaviour quicksmart.

Other researchers, chief amongst them Menolaos Apostelou, have wondered whether we should look more closely at how parents choose partners for their offspring. This is still a common practice in many cultures, and was probably even more common in the past. The good thing is that we can investigate multiple areas: female choice, male choice, parent choice, sibling choice -- even the effects that offspring have on the choices of their parents. They're all likely to have a part to play.

No doubt prehistoric women could exercise some degree of mate choice otherwise they wouldn't have evolved sexual preferences of their own. It's just that I believe that a lot of pop evo-psych books I've read overestimate how free women were in prehistory to choose mates. The authors seem to imagine that prehistoric people behaved and chose mates like middle class people do today but just happened to live out in the jungle.

In his book The Mating Mind, Geoffrey Miller paints a picture of prehistoric mate choice as being like the female choice dominated system seen in many bird species. He imagines that men would display to the women who would then choose which men to mate with. As a result, he supposes, men have evolved sexual ornamentations to impress women with, analogous to the brightly coloured feathers and singing talents of many male birds.

Now, this is complete fantasy. If men have been heavily sexually selected for hundreds of thousands of years then by now we'd all be tall, handsome, super sexy Casanovas with big willies and silver tongues. There's really little evidence that female choice has been a big driving force in recent human evolution. Although it makes perfect sense for women to try to act as gatekeepers to their eggs, the degree to which they were actually able to do so in prehistoric societies has probably been overestimated by many people and most of mate choice in prehistory was probably males choosing females not the other way round.

I think you're probably right that researchers have not investigated male choice as much as they could, although that might be changing somewhat now. Humans are a cooperatively breeding species, so we would expect to see strong choice by both males and females, and it just happens that most people have decided to look at female choice so far.

What you say about penis size is interesting because I believe that humans have the largest penises of any primate. It's not clear that women prefer men with larger penises (at last, I've not read a convincing paper on that subject), but it's possible that female choice has played a role here. It's also possible that penis size is driven by sperm competition, where multiple men compete to impregnate the same women. I think I have also read that men's relatively neotenous facial features (compared to those of, say, gorillas) are down to female choice. If male faces structure was driven purely by male competition we might look tougher and more brutish. And, of course, men do tend to be taller than women and height is something women value. So perhaps we are tall, handsome, and well-endowed!

Anyway, whether most mate choice was male or female in the EEA is a question I am not equipped to answer. That's going to take someone a lot smarter than I am! In the meantime, I'm happy researching what men and women prefer in a partner. Simple stuff!